1. Field of the Invention
The present invention relates to a device and a method of arbitrating a cell bus for transmitting data in a certain size of packet unit, and more particularly, to a cell bus arbitration device and method of allowing the right to use a cell bus effectively to multiple service entities in the cell bus, in which the multiple service entities are connected in parallel, and of arbitrating the cell bus by first-in-first-out function and service use records.
2. Description of the Prior Art
In the priority art, the conventional methods arbitrating a cell bus are classified according to the following three types: firstly, a method by daisy chain representing the method being used in a VME bus of Motorola; secondly, a distributed bus arbitration method; and, thirdly, a full-connected-bus arbitration method (Refer to "Advanced Computer Architecture" by Kai Hwang).
The method by daisy chain arbitrates a bus by that multiple entities connected a common bus share and request a bus request line, and connect bus acceptance signals from a bus arbiter by daisy chain.
The distributed-bus arbitration method is that each entity has its inherent ID and supplies the ID according to the request of a bus, but a entity having a low-valued ID has the right using the bus before others at the collision of IDs.
The full-connected-bus arbitration method is that each entity has separately a bus arbiter, a bus request signal and a bus use signal line, and bus arbitration is accomplished by multiple algorithms in the bus arbiter.
However, among the bus arbitration devices in the conventional full-connected-bus arbitration method as described in the above, there is a problem which it is impossible to allow the uniform right to use a bus to all entities because the first-in-first-out function having been used until now is applied simply and a entity requesting use of the bus frequently over-occupies the bus one-sidedly.